BoilerTroubleshooting2026-02-26
Boiler Overheating: Causes and Risks
Overheating usually means poor circulation from sludge, a stuck pump or a faulty thermistor.
A boiler that overheats and locks out is signalling a circulation or sensor problem.
Why it overheats
Sludge or a failing pump restricts water flow so heat can't dissipate; a faulty thermistor can also misread temperature and trigger lockout.
What to do
A power flush and pump check often resolve circulation-related overheating; sensor faults need replacement.
Key takeaways
- Often a circulation problem
- Power flushing can resolve it
- Check the pump and thermistor
- Don't ignore overheating lockouts
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